Capacitor construction and circuit arrangement for polyphase circuits



y 9 3- M. I. ALIMANSKY 2,317,970

. CAPACITOR CONSTRUCTIOI AND cmcun ARRANGEMENT Foa tomrrms's cmcuns Filedioh. 15, 1940 N X VOLT-5 A mto lnventcr:

Max L' Al irhcnskg,

. Hls Attorney.-

Patented May 4, 194-3 CAPACITOR CONSTRUCTION AND CIRCUIT ARRANGEMENT FOR POLYPHASE CIR- Max I. Alimansky, Pittsfield, Mass., assignor to General Electric Company, a corporation of New York Application February 13, 1940, Serial No. 318,723

19 Claims.

The present invention relates to application of capacitors to polyphase alternating current circuits for power factor improvement or other purposes, and has for a general object the provision of improvements in construction and circuit connections for capacitors so applied.

One of the more specific objects of the invention is the provision of an improved 3-phase capacitor unit which may be employed singly on a polyphase circuit operating at a voltage corresponding substantially to the voltage rating of the capacitor unit, and which unit is adapted for employment also with other capacitor units of similar construction on polyphase circuits operating at voltage which are multiples of the voltage rating of the single capacitor unit.

Another of the specific objects of the invention is the provision of simple and readily convertible connection arrangements for connection of capacitor units, such as referred to above, in polyexemplary form of capacitor unit employed with the present invention, Fig. 2 illustrates diagrammatically the internal connections of the capacitor unit of Fig. l and the manner of connecting such unit in an electric circuit in accordance with one aspect of the invention, and Fig. 3 illustrates diagrammatically the manner of connecting two such units in an electric circuit in accordance with another aspect of the invention. It is to be understood that all references made herein to specific k. v. a. ratings and voltages are for purposes of example only, since the present invention is not limited to any particular k. v. a. rating or voltage.

It sometimes occurs that it is desired t apply capacitors to an electric system operating at a certain voltage, with provision for employment of the same capacitor unit in case the electric system later is converted to higher voltage service. In some cases, particularly where it is desired to apply capacitance in blocks of small k. v. a., this may present difliculties due to the fact that capacitor units commonly are manufactured and supplied only in certain standard ratings. For example, it may be desired to apply capacitors in blocks of small k. v. a. to a plant feeder system which is operating at 230 volts, but which is to be converted to 460 volts, and at the same time it may be found that it is most desirable for economical or other reasons to utilize standard capacitor units of 230 volt, 5 k. v. a. rating. Usually capacitor units are made available in the standard ratings for operation single-phase, 2-phase, or 3-phase. In the example mentioned, a heretofore common form of capacitor unit, of a standard 230 volt, 5 k. v. a. rating and internally delta-connected for B-phase operation, might be employed initially to give the desired small k. v. a. at any one point of capacitor application on the 230 volt, 3-phase system. However, such a capacitor unit would not be suitable for employment, as by connection in series with another similar capacitor unit, when the system is converted to 460 volts. A standard 5 k. v. a., 3-phase capacitor unit of 460 volt rating might be employed initially with some formv of voltage conversion apparatus, but this would require additional equipment which would be discarded when the 230 volt system is converted to 460 volts. Another alternative would be the employment of three standard 230 volt, 5 k. v. a., single-phase capacitor units, each connected across a respective one of the phases of the 230 volt circuit. Then upon conversion to 460 volt service, the original three capacitor units could be used with the addition of three similar units, with two of the units connected in series across each one of the phases of the 460 volt circuit. However, in this last case, the three single-phase unit originally employed for 230 volt service would provide a block of 15 k. v. a., while the six units employed for 460 volt service would provide a block of 30 k. v. a., which might be too high in view of a desire to limit the application of capacitors to small k. v. 9.. blocks.

In order to overcome in a simple and economical manner the difiiculties above referred to, I have provided an improved form of 3-phase capacitor unit and improved circuit connection arrangements therefor, now to be described.

An exemplary form of capacitor unit employed with the present invention is shown in side elevation in Fig. 1 and generally designated It. In fundamental construction, this unit may be of a form well known in the capacitor art, such as, for example, comprised of layer of metal foil and dielectric spacing material wound into a number of rolls which are flattened and arranged in side-by-side relationship in suitable enclosing casing containing a liquid insulation material, such as that known as pyranol, or other suitable filling medium. For the purposes of the present invention, the casing of the capacitor unit is provided with four bushing supported terminal studs designated II, I2, I3, and I4 respectively, and the foils of the internal assembly of the unit are electrically grouped in any well known manner so as to provide three sections I 5, IB and I! of equal capacity, as diagrammatically indicated in Fig. 2. It will be understood of course that each of these sections may comprise one or more rolls of the internal assembly. For purposes of description the-oppositepotential poles of section I5 are designated as I8 and I9, the poles of section I6 as and ZIand the poles of section I! as 22 and 23. Pole I9 of;section I5 is electrically connected with pole 2B of section It at a common point designated Zi which is electrically connected with terminal stud II. The other pole, 2|, of section it is electrically connected with one of the poles, 22, of section I1 at acommon point 25 which is electrically connectedwith terminalstud I4; The-remaining .,pole, I3, of section I5 is electrically connected .With terminal stud I2,-while the remaining pole,

23; of section-I1 is electrically connectedwith terminal stud I3." Thus, there is-produced in effeet a delta-connected circuit arrangement with one of the corners of the delta left open and brought out forthe making ofgccnnections externally of the casing of the capacitorunit'. This capacitor structure is, described, and-claimed in [my copending application s. N 408,367, filed August 11, 1941, and assigned to the same assignee as thepresent invention.

I InFig. 2 there is diagrammaticallyillustrated a connectionarrangement iorapplication of a capacitor unit, as described above, to a 3phase alternating current circuit havingphase conductors A, B, and C and avoltagetebetween the n phase conductors approximately equal to the voltage ratingof the capacitor unit.- In this case, a suitable form of conductive jumper,;indicated 'at 26, is removably connected between terminal studs I2 and it so, as externally to complete the delta circuitarrangement of the capacitor sec- 'tions I5, lfi andl'i. Terminal studs Ii, I3, and I 4 are shown diagrammatically asbeing connected with phase conductors C, B,- and A; re-

spectively; Thus, section 15 is connected across phase 3+0, section it isconnected across'phase A'C, and section I3 is connected across phase -NOW, if it is desired to employ acapacitor unit, such as that designated ion a 3-phase circuit operating at a voltagesubstantially double the voltage rating of -the;capacitor unit, this may be nected With-terminal I3 of unit it by means of l a jumper 3 t. Then terminal I iof unit it is connected with-phase conductor jumper 31 is ---connected with phase-conductor B, and terminal I I" of unit I 5' is connectedWi-th phase conductor C Thus, sections i5 and I6 of unit It are con- In such case, the Jumper lit-between nected in series with each other and across phase A-B, and sections I6 and ll of unit I8 are connected in series with each other across phase B-C, while the remaining section ll of unit I0 is connected in series with the remainingsection I5 of unit I d across phase AC. This completes a. delta-circuit arrangement leaving two of the capacitance sections in se ies in each side or phase of the delta.

From the foregoing, it will be seen that by reason of the present invention, it is made possible a to employ a single capacitor unit of small k. V. a.

ing of one of the units. capacitor constructed inaccordanc rating inthe application of capacitance to a 3-phase circuit operating at a voltage substantially the, same as the voltage rating of the capresent invention and having a volts, 5 1;. v. a., may be applied to a 3-phase circuit operating at approximately 28:) volts, in the manner shown in Fig. 2, while two oi such capacitor units, each having-a rating 239 volts, 5

k. v. a., may be connected in series inthe inanner shown in Fig. 3 for application to a-B-phase circuit operating at approximately 460 voits.

.However, it is to be understood that the present invention is not limited necessarily to-application. of capacitance in small 1:. v; blocks.

A will be evident to one .killed in the ar-t-,-several capacitor units, such as the one-designated may be connected inparallel for application to a B-phase circuit in a manner similar to that shown in Fig. 2, if large blocks of'c-apacitanceare desired. Likewise, for the'circuit arrangement illustrated in Fig. 3, there may be employed either two identical units, as illustrated, or multiples oi two, if larger blocks of capacitance are-desired.

heretofore mentioned.

. A further advantage or" my invention is that capacitor units for use in the practice of the invention require no special expensivedesi-gn and .may be made to have very nearly the-same fundamental construction as standard forms of three-phase capacitor units heretofore common in the art. fhus, standard parts may be used practically exclusively andtalready. established assembly machines and routines may be availed of, so that simplicity and economy of manufacture is obtained.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In combination .with a three-phase alternating current circuit, a capacitor unit having three electric capacitancesections and four terminals for connection of said sections in said circuit; one of said terminals being commonto one pole of one of said sections and one pole of a secthreeofsaid terminals, connecting allof said sections for supplying capacitance to said threephase circuit.

2, In combination with a three-phase alterhating current circuit, a capacitor unit having three electric capacitance sections and four connection terminals therefor; one of said sections being connected between. one pair of said terminals, a second of said sections being connected between the other pair or" said terminals, the third of said sections being connected between one terminal of said one pair and one terminal of said other pair; and means, employing at least three of said terminals, connecting all of said sections in a delta-circuit arrangement for supplying capacitance to said three-phase circuit.

3. In combination with a three-phase alternat ing current circuit, a capacitor unit having three electric capacitance sections and four connection terminals therefor; one pole of one of said sections and one pole of a second of said sections being interconnected and having one of said terminals in common, the other pole of said second section and one pole of the third of said sections being interconnected and having a second of said terminals in common, the third and fourth of said terminals being connected respectivel with the remaining pole of said one section and with the remaining pole of said third section; means connecting said one terminal and said second terminal each with a respective one of the phase conductors of said circuit, and means connecting both said third terminal and said fourth terminal with a third one of the phase conductors of the circuit.

4. In combination with a three-phase alternating current circuit, a plurality of capacitor units; each of which units has three electric capacitance sections and four connection terminals therefor, with one of the terminals common to a pole of one of the sections and a pole of a second of the sections, another of the terminals common to the other pole of said second section and a pole of the third of the sections, and the remaining two of the terminals connected respectively with the remaining pole of said one section and with the remaining pole of said third section; and means interconnecting certain of the terminals of two of said units and connecting the conductors of said three-phase circuit with certain of the terminals of said two units in a manner to complete connection of the six sections of said two units in a delta-circuit arrangement with a respective two of the six sections in series across each of the phases of the circuit.

5. In combination with a three-phase alternating current circuit, a plurality of capacitor units each having three electric capacitance sections, means connecting the six sections of two of said units in a delta-circuit arrangement havin a respective two of said siX sections in series in each side of the delta, and means for supplying the capacitance of each side of the delta to a respective one of the phases of said three phase circuit.

6. In combination with a three-phase alternating current circuit, two similar capacitor units each having three electric capacitance sections and connection terminals therefor, and means connecting a respective two of the sections of said units in series across each of the phases of said three-phase circuit.

'7. In combination with a three-phase alternating current circuit, a plurality of capacitor units each having three electric capacitance sections and connection terminals therefor, and connection means for supplying the capacitance of two serially connected sections of one of said units to one of the phases of said circuit, the capacitance of two serially connected sections of another of said units to another phase of said circuit, and the capacitance of the serially connected remaining sections of said one unit and said other unit to the third phase of said circuit.

8. In a capacitor assembly for supplying capacitance to a three-phase circuit, two similar capacitor units each of which has three electric capacitance sections and connection terminals therefor, and means interconnecting certain of the terminals of one of said units with certain of the terminals of the other of said units in a manner to complete connection of the six sections of said two units in a delta-circuit arrangement with a respective two of the sections in series in each side of the delta.

9. In a capacitor assembly for supplying capacitance to a three-phase circuit, two similar capacitor units; each of said units having three electric capacitance sections and four connection terminals therefor with one of the terminals common to a pole of one of said sections and a pole of a second of said sections, another of the terminals common to the other pole of said second section and a pole of the third of said sections, and the two remaining terminals of the unit connected respectively with the remaining pole of said one section and the remaining pole of said third section; and means electrically interconnecting each of the said two remaining terminals of one of said units with a respective one of the said two remaining terminals of the other of said units.

MAX I. ALIMANSKY. 

